We have a computer at work that runs on Windows 7 and I needed to check whether it can connect to our internal SMTP server so I can use it to send emails. The quickest way to do this is to telnet to the SMTP server on port 25 but it turned out telnet is disabled/not installed by default on Windows 7. It gave the message “‘telnet’ is not recognized as an internal or external command, operable program or batch file.”

Here’s how to enable it:

1. Go to Control Panel -> Programs.
2. Under Programs and Features, click Turn Windows features on or off.
3. Check Telnet Client and click OK.

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